I have made a few parts which have a few pin holes, whats the best/easiest method for removing these, do you just mix a bit of resin with fast hardener and keep applying until the hole is filled and then flat off or is there a better method? 

The pdf will give you enough info to get started. I would suggest you log the cure schedule you run and fine tune it from there. Using a ramp and dwell controller would be really helpful too. 

They will do smaller quantities. Not sure if they have a minimum as I now order at least 20 meters usually 25 meters as some of my work is not material heavy but is time consuming so I get enough to make sure I do not have issues with outlife.